As was stated in prior U.S. patent application Ser. No. 07/997,797 filed on Dec. 29, 1992, in the names of Bernard Cohen, Lee Jameson and Robert Isaac, for many years the problem of waste disposal has plagued the industries which provide disposable diapers, incontinent garments and feminine care products. While much headway has been made in addressing this problem, one of the weak links has been the inability to create an economical plastic material which will degrade when exposed to natural environmental forces. In particular, those of skill in the art have long sought materials which have the ability to readily dissolve, disperse or disintegrate in water. See, for example, U.K. patent disclosure 2,246,373, U.S. Pat. No. 4,186,233 and European Patent Application Number 0 585 906 A2. Without such a material the ability of the user to dispose of a product by flushing it down the toilet is controlled by the physical geometry of the product and the material handling capabilities of the sewage system and plants which will handle the product. Naturally, these constrictions greatly reduce, if not eliminate, the types of products which can be disposed of via toilet flushing. Furthermore, the ability of products such as disposable diapers, incontinent garments and feminine care products, to disintegrate in a landfill has been quite limited. This is because, historically, a large portion of the components of these products, which may well be biodegradable or photodegradable, are encapsulated in a plastic material which only degrades over a long period of time, if at all. Accordingly, if the plastic at least disintegrated in the presence of water, the internal components could degrade as a result of the rupture of the plastic encapsulation and their subsequent exposure to the forces of natural degradation.
The prior U.S. patent application, Ser. No. 07/997,797, discloses such a material and products formed thereby. The terminology used to describe such a material in that application was "hydrodisintegratable". For purposes of consistency, that terminology will also be adopted for use in the present application. The entirety of U.S. patent application Ser. No. 07/997,797 is hereby incorporated by reference.
One of the areas of interest for applications of such a material is, as was stated above, in feminine care items such as, for example, tampons. In some instances, women attempt to discard the rigid or semi-rigid jacket (typically called the applicator) that holds the tampon by flushing it down a toilet after the tampon has been inserted. Because tampon applicators typically are manufactured from a rigid or semi-rigid plastic material which, at best, only slowly degrades in the environment, this method of disposal has created at least two problems, both of which have plagued society for several years. First, such a method of disposal can lead to clogging of toilets or drain pipes. For this reason, many women, after having experienced a sewage line clogging, have refrained from this method of disposal. The second problem results from the resistance of the applicator to the degrading forces of nature whether they be physical or biological. Municipal waste treatment plants typically do nothing to degrade or otherwise alter the applicator. Accordingly, applicators are released into the environment by these plants in a generally nondegraded state. That is, they are readily recognizable as tampon applicators. Such released applicators show up on the banks of rivers and streams and even are deposited by ocean currents and tides. Of course, those applicators that do find their way to a landfill do not readily degrade in that environment either. Naturally, this result is quite unacceptable from both environmental and aesthetic standpoints.
In conducting additional work with the material disclosed in U.S. patent application Ser. No. 07/997,797, it was discovered that the material generally disclosed therein, while quite satisfactory for use in, for example, film formation, exhibited distinct shortcomings when attempts were made to injection mold the material into shaped products. Typically, the material either: (1) assumed a physical, that is geometrical, configuration which did not satisfactorily conform to that desired by, for example, curling or otherwise physically deforming; or (2) became quite brittle and thus was too fragile to form a satisfactory commercial product.
Accordingly, those of skill in the art developed the view that this material was not satisfactory for use in the formation of injection molded objects. Because of the desirable hydrodisintegratability characteristic of this material, those of skill in the art sought a solution to the problems associated with injection molding the material. The starting point of this quest was the appreciation that products molded from this material either physically deformed as by, for example, curling or otherwise assuming a physical shape which did not conform to the desired shape or became brittle during molding, but never both.